https://www.gov.uk/government/news/pms-european-council-press-statement-20-october-2017
https://publications.parliament.uk/pa/ld201719/ldselect/ldeucom/15/15.pdf
https://ec.europa.eu/commission/publications/position-paper-essential-principles-financial-settlement_en
https://publications.parliament.uk/pa/cm201719/cmselect/cmexeu/1778/1778.pdf